The Determinants of Activated Partial Thromboplastin Time,Relation of Activated Partial Thromboplastin Time to Clinical Outcomes,and Optimal Dosing Regimens for Heparin Treated Patients with Acute Coronary Syndromes: A Review of GUSTO-IIb

Context: Unfractionated heparin remains widely utilized in the treatment of acute coronary syndromes (ACS). However, limited data exist on optimal dosing and range of activated partial thromboplastin time (aPTT) in this setting. A large trial of thrombolysis for acute myocardial infarction has reported an association between longer aPTTs and adverse outcomes. Objectives: Estimate the optimal heparin-dosing regimen in achieving early therapeutic aPTTs (50 to 75 seconds) and determine the association of aPTT and death, reinfarction, and bleeding in population with ACS. Design: Subgroup analysis within a randomized, controlled trial of 5861 patients given unfractionated heparin who had aPTTs at 6, 12, or 24 hours, with outcome analyses by weight categories. Setting: In 373 hospitals in 13 countries from May 1994 to October 1995. Patients: A total of 12,142 patients admitted for ACS, stratified by the presence (n = 4131) or absence (n = 8011) of ST-segment elevation, and randomized to 72 hours of unfractionated heparin. Results: In a simulated weight-adjusted model, based on retrospective grouping by weight, a simulated dose of 60-U/kg bolus and 12-U/kg/h infusion resulted in the highest proportion of therapeutic aPTTs. After adjustment for baseline variables, longer 12-hour aPTT was associated with the composite of 30-day death or reinfarction in patients not treated with thrombolytic therapy (odds ratio, 1.10; 95% CI, 1.00 to 1.22; P = 0.047). Longer aPTT at 6 hours was associated with increased moderate or severe bleeding for the entire cohort. There was also a significant, nonlinear correlation of the 12-hour aPTT with moderate or severe bleeding in thrombolysis-treated patients. Conclusions: For ACS patients who are treated with heparin, aPTT is highly associated with body weight. Longer aPTT within the first 12 hours is associated with adverse outcomes in ACS. Heparin dosing for ACS should be weight based.     

Clinical,Angiographic, Functional,and Imaging Outcomes 12 Months After Implantation of Drug-Eluting Bioresorbable Vascular Scaffolds in Acute Coronary Syndromes

ObjectivesThe purpose of this study was to describe the multimodal outcome 12 months after implantation of coronary bioresorbable scaffolds (BVS) for the treatment of patients with acute coronary syndromes (ACS).BackgroundFunctional and imaging data on the use of BVS are limited to simple, stable lesions; in the setting of ACS, only short-term clinical follow-up data are available, and no information from intracoronary imaging and vasomotion tests has been reported.MethodsA total of 133 patients (age 62 ± 12 years, 74% males, 15% diabetic) underwent BVS (n = 166) implantation for the treatment of thrombotic lesions in the setting of ACS (43% non–ST-segment elevation myocardial infarction, 38% ST-segment elevation myocardial infarction, 20% unstable angina). Clinical, angiographic, intracoronary imaging, and vasomotor endpoints were evaluated at 12 months.ResultsDuring the 374 days (interquartile range: 359 to 411 days) of follow-up, there were 4 deaths; 3 definite and 1 probable in-BVS thromboses (all in the first 6 months). At 12-month angiography (75 patients, 83 BVS), in-segment late lumen loss was 0.19 ± 0.45 mm, and 3 (4%) patients showed binary restenosis. Optical coherence tomography (80 BVS, n = 70) showed a mean lumen area of 6.3 ± 2.3 mm². Malapposition was evidenced in 21 (26%) BVS. Endothelium-dependent and -independent vasodilation were observed in 48% and 49% of the BVS.ConclusionsTwelve months after BVS implantation, clinical, intracoronary imaging, and vasomotion data appear to provide a rationale for the use of BVS in the setting of ACS and the basis for a randomized study.